Volume 1 — GENERAL DISEASES. (continued 23)

In conclusion, it must be urged that the similarity of the symptoms in many epidemics, occurring during the course of several centuries and under different social conditions, and even different degrees of civilization, forcibly demonstrates the specific and definite character of the causes which give rise to influenza.

Very little light is thrown upon the pathology of the disease by the anatomical changes found after death. Uncomplicated influenza is rarely fatal. As a rule, the unfavorable termination is due to lung complications. The essential lesions are congestion and catarrhal swelling of the mucous membrane of the upper air-passages and the bronchial tubes. These changes may be restricted, in the lungs, to the trachea and larger bronchi, or they may extend to the finest twigs. They may amount to great thickening and deep capillary injections of the mucous lining of the tubes, which contain clear, frothy mucus or thick, viscid masses of muco-purulent secretion unmixed with air.

More or less congestion of the gastric mucous membrane, and more rarely of that of the intestine, is also met with. The solitary and agminate glands of the intestine are not affected, save as the result of special complications. A few observations relate to the finding of enlarged and softened bronchial glands. More extended researches are needed, not only upon this point, but also in the whole domain of the pathological anatomy of the disease.

Hyperæmia, oedema, hypostatic congestions, splenization, catarrhal pneumonia, and hepatization affect the lung-tissue in cases fatal by the complications which are associated with such changes. The tissue-changes of diseases existing prior to the attack of influenza, such as old consolidations, tubercle, brown induration, emphysema, and so forth, are of course frequently discovered.

DIAGNOSIS.—The discrimination of influenza from other affections having some points of resemblance to it is, under ordinary circumstances, unattended with difficulty. The march of the epidemic, the number of persons attacked, the prominence of the nervous symptoms, the rapidly developed debility, and the character of the cough, usually severe out of proportion to the physical signs, distinguish it from all other epidemic diseases.

It is to be differentiated from non-specific catarrhal affections attended by fever, malaise, weakness, severe headache, and pain in the extremities by a due regard to the causative relations of the two affections. Simple catarrhs not rarely present the group of symptoms which characterize epidemic catarrhal fever, but they occur almost constantly as the result of great and sudden changes in the weather, and are therefore met with in greatest frequency in bad seasons, and are particularly common at the end of winter and in the spring. Influenza is not in any way dependent upon the vicissitudes of the seasons, and may occur, as has been shown, at all times of the year, in wet or dry, mild or cold seasons equally, and in every variety of climate. It is of course diagnosticated without difficulty from the sporadic catarrhal fevers, which lack the characteristic depression, neuralgic and rheumatoid pains, the irritative cough, dyspnoea, and so on.

Cases of influenza are met with that bear a strong resemblance to beginning enteric fever. The malaise, headache, obtunded hearing, mental depression, high fever, coated tongue, tender belly, diarrhoea, are symptoms to be observed in both affections. But influenza lacks the temperature curve, the splenic enlargement, and the eruption of enteric fever, and the progress of the disease will in a few days clear up the most doubtful case.

PROGNOSIS AND MORTALITY.—Death is rare in uncomplicated cases. The very young bear influenza badly; the old bear it more badly still. Nevertheless, children have in some epidemics enjoyed a considerable proportionate immunity. Healthy persons in the middle periods of life bear it well. Certain pre-existing diseases modify its course unfavorably; among these are chronic bronchitis, emphysema, fatty heart, and Bright's disease. The debility of advanced phthisis and other exhausting diseases renders influenza dangerous. Death takes place, in by far the greater number of cases, as the result of the complication of the attack, either by some pre-existing affection or by an acute disease arising in its course. The commonest of the latter are inflammations of the parenchyma of the lungs.

Patients presenting very severe symptoms generally recover if they be not the subjects of complicating maladies or very young or very old.

Relapses are not uncommon; independently of relapses, second attacks have been known to occur during the continuance of an epidemic; it is often the case that an individual in the course of his life passes through several epidemics of influenza, and is the subject of the disease in each of them.

The prognosis is greatly modified by the character of the prevailing epidemic. In some epidemics the deaths are few, and the mortality from other diseases does not appear to be greatly augmented. In others many die of the epidemic disease, and the death-rate of certain endemic affections is much increased. In some of the older epidemics the high mortality was doubtless due to injudicious measures of treatment, among which bloodletting and other depressing agencies were conspicuous. Some of the older accounts also warrant the suspicion that a coexisting typhus had to do with the high death-rate. It is estimated that in the epidemic of 1837, which was a very severe one, 2 per cent. of those attacked died. The proportion of fatal cases in particular epidemics varies in different countries, and even in different quarters of the same city.

TREATMENT.—Efficient measures of prophylaxis are as yet unknown. Unfavorable hygienic surroundings, overcrowding, a damp, unhealthy locality, appear to increase the prevalence and severity of influenza. The opposite conditions of living do not, however, secure immunity from the attack. During an epidemic aged persons, those enfeebled by chronic diseases, and in particular those subject to chronic bronchitis, consumption, emphysema, fatty heart, and Bright's disease should be cared for with unusual diligence and solicitude, since they constitute the classes most prone to the graver complications of the disease, and from which its fatal cases are almost wholly derived. Such individuals should be warmly clad; they should shun, so far as possible, the vicissitudes of the weather, even, if practicable, keeping within warmed and well-ventilated apartments; they should exercise unusual prudence in diet and lead a carefully regulated life, with long hours of sleep. It is true that these measures are not preventive of the attack. Families not quitting the house, living in the greatest seclusion, even the bedridden, do not always, or even as a rule, escape. Yet it has frequently been observed that those whose occupations are carried on in the open air are attacked earliest and in greatest numbers. On the other hand, in rare instances, persons isolated from the community with strictness—in prisons, cloisters, hospitals—have remained free from the disease prevailing around them. It therefore appears probable that, under certain favorable circumstances not as yet perfectly understood, the avoidance of the open air and of the direct influences of the weather may confer some degree of immunity from the attack, and it is desirable that the class of persons most liable to the graver consequences of the disease should avail themselves of even the most uncertain precautions.

The treatment of influenza is expectant and supporting. Not only is the epidemic self-limiting, tending to exhaust the susceptibility of a community, in most instances, in the space of a few weeks, but the attack is also of definite duration, and the perturbations set up by the action of the influenza-poison upon the individual subside spontaneously in three or four, or at most ten or twelve, days. The susceptibility of the individual is also, for the time being, exhausted, for second attacks in the same epidemic are not very common. In cases where the duration of the attack is prolonged beyond the period indicated, it is kept up by complications, and we have to do not so much with the pathological processes of influenza as with secondary diseases that the influenza has excited either by the intensity of its action or by reason of some peculiarity of the subject of the attack.

By far the greatest number of cases are light and unattended by danger. The treatment is therefore, for the most part, an extremely simple one. These lighter cases seldom require medical measures. The patients are uncomfortable and anxious, easily fatigued, and unfitted for business. It is best that they keep the house, and, if willing, the bed or sofa, for the space of two or three days. The diet should be restricted to a few simple and easily-digested dishes. Meat should be avoided. The common custom of taking hot beef-tea is an extremely bad one; it often increases the headache and languor. Moderate quantities of cold drinks may be taken. The fruit-syrups, lemonade, raspberry vinegar, a weak solution of citrate of potash or of cream of tartar, and barley-water with lemon, are useful. Very weak wine-whey is often liked. The effervescing mineral waters or Apollinaris are preferred by many persons. The best of such drinks is a mixture of equal parts of Seltzer-water and milk, iced. If the stomach be irritable, koumiss will be found an excellent beverage and food. In the mild cases stimulants are not necessary. Sound claret, with or without Seltzer-water, is not contraindicated. In all cases the amount of fluid taken should be moderate.

Quinine in moderate doses should be taken from the onset. The head-pains are not increased by it. Dover's powder, if well borne, should be administered at night. Some form of opiate may be required, even in mild cases, to counteract wakefulness. A compressed pill, containing extract of opium 0.030 gramme (gr. ½), camphor 0.15 (gr. ij), and ammonium carbonate 0.15 (gr. ij), will be found useful when Dover's powder cannot be employed. During convalescence iron and barks are often requisite.

The coryza, tonsillitis, laryngitis, bronchitis are to be treated according to general principles, if they require treatment at all. In most mild cases the catarrhal symptoms call for no special measures of treatment.

Free inunctions of fatty substances about the brow and over the bridge of the nose are of use as regards the coryza. For this purpose animal fats, washed lard, simple cerate, cold cream, and the like are to be preferred to cosmoline and vaseline.

Morphine dissolved in cherry-laurel water, one part in fifty or sixty, is useful for the relief of the head-pains associated with the coryza. A few drops may be snuffed up from time to time. These pains are mitigated to some degree by wearing a flannel cap or wrapping the head in a silk handkerchief. Warm applications sometimes give comfort, while cold almost invariably add to the distress.

Distress in the upper air-passages and the tickling cough call for steam inhalations, and the air of the apartment may be rendered moist by the evaporation of water kept boiling in a broad, shallow vessel. Gargles of potassium chlorate, or potassium chlorate with sumac, exert a soothing influence upon the congested tonsils.

Severe cases call for more energetic measures of treatment. The most prominent indications are the control of the fever; the diminution of the hyperæmic fluxion to the mucous tracts; measures of support; the mitigation of pain and the induction of sleep; and, finally, the prevention of the pulmonary congestion, to which the depression leads by enfeeblement of the circulation. The last indication is especially urgent in infants, the very old, and those previously debilitated from any cause.

Inflammatory complications require special treatment or modifications of treatment.

The febrile movement is not, as a rule, high; grave nervous symptoms and serious catarrh may be associated with moderate fever.

An anti-febrile regimen is to be observed. The moderate duration of this fever, as compared with enteric fever, renders it less important that large amounts of fever-food should be given, while the tendency to depression makes it of the utmost importance that the administration of food be systematic and carefully looked after by the medical attendant. The disinclination to take food is so great that it is often with difficulty that a sufficient quantity can be given in the early days of the attack, and it is to be doubted whether benefit follows anything in excess of the most moderate amount. It is necessary to observe regular hours, as in the management of all the low fevers. As soon as convalescence begins the patient should be urged to eat; the quantity of food taken at one time is to be augmented, and the intervals between the meals may be longer.

A favorable action upon the excretory function of the skin and kidneys will result from the moderate drinking of water or of the beverages already spoken of. At least enough fluid should be taken to relieve thirst.

Diaphoretics have been much used, upon the theory that by determination to the skin they correspondingly diminish the tendency to hyperæmia of the affected mucous tracts. Dover's powder, solution of the acetate of ammonia, and other mild diaphoretics are to be selected. Jaborandi should be employed with caution. The wet pack and other hydrotherapeutic measures have been employed to act upon the skin and to effect a direct reduction of temperature in influenza. For old and feeble persons warm packs are employed. A profuse sweating at the onset of the attack is said to occasionally cut it short. Early diaphoresis often brings about a rapid and lasting amelioration of the symptoms. It is to be borne in mind that the fever is rarely excessive, and that sweating is not infrequently a troublesome symptom. In some epidemics it has been a very troublesome one.

General bloodletting is not to be resorted to in influenza. Its danger was apparent to some of the early writers. As has been pointed out, the high mortality of some of the older epidemics is to be explained by the venesections practised at the beginning, and even during the course, of the attack. It has no favorable effect upon the catarrhal processes, and but little upon the subjective symptoms. The fever is not relieved by it; the nervous depression is increased and the risk of lung-congestion is augmented. Bleeding is not likely to be practised in epidemic catarrhal fever while the present views of its place in therapeutics continue to influence practice. Cautious local bloodletting for the relief of local inflammatory trouble is spoken of in most of the modern books. The occasions for its employment are so rare in the treatment of this disease that even this statement should be henceforth omitted. In influenza, as it is known to medical men of the present from the descriptions of the old and personal experience of the few recent and milder epidemics, bloodletting, either general or local, is clearly uncalled for.

Emetics hold a high historical place. It was of old customary to begin the treatment with a vomit. As late as the epidemic of 1837, Lombard of Geneva believed that they shortened the attack and lessened the intensity of the symptoms when administered at the beginning. In cases attended by early gastric disturbance and nausea they are said to be especially of use. They sometimes set up great irritability of the stomach, with vomiting that it is difficult to control. On the whole, the cases in which an emetic would do good are extremely rare.

Purgatives were formerly regarded as important in the treatment. This view no longer prevails. In case of constipation gentle purgation, ex indicatione symptomaticâ, is a necessary part of the proper management of the case. For this purpose the laxative mineral waters, as Friederichshalle, Hunyadi, Pullna, are excellent. Castor oil may be given, and calomel is in some cases, and particularly in childhood, of great service. Simple enemata of warm water or soap and water will often suffice. The tendency in some cases to exhausting and troublesome diarrhoea, and the fact that diarrhoea occurs spontaneously some time in the course of most cases, should inspire caution in the use of purgatives. Repeated purgation during the progress of the attack is not only useless—it is also positively injurious.

In the severe cases quinine is to be given early and in full doses. It exerts at the same time a powerful influence upon the temperature, upon the tendency to local hyperæmias, and upon the nervous symptoms, and in particular the headache. Rawlins,²³ as early as 1833, found that excellent results followed its administration, the effect being the better the earlier it was given. It has even been lauded as a specific for influenza.

²³ London Medical Gazette, May, 1833.

The mineral acids may be given with a view to realizing their tonic effects.

For the most part, the foregoing measures, directed against the fever, will exert a favorable influence upon the catarrhal processes. Expectorants are of advantage; ipecac is useful. The preparations of antimony are inadmissible by reason of their tendency to depress. Ammonium chloride is indicated in the earlier stages of the bronchitis. Among recent drugs, yerba santa (Eryodiction glutinosum) and the oil of eucalyptus are of use in mitigating the symptoms in epidemic catarrh, as they do in certain forms of simple sporadic catarrh.

The peculiar dry, racking cough so often present in the early days of the attack should be relieved. It is not useful in removing bronchial accumulations, being, as has been shown, in most instances out of proportion to the lesions of the bronchial mucous membrane; on the other hand, it tends to increase the hyperæmia of the upper air-passages by the mechanical violence of the cough-paroxysms. Further, it is distressing and exhausting, and contributes to the muscular and nervous prostration. Benefit will be derived from keeping the air of the apartment moist, and from the occasional inhalation of the steam from hot water, either used alone or poured upon the compound tincture of benzoin, a pint to the teaspoonful, or upon paregoric, a pint to the tablespoonful, in a proper vessel or inhaler.

No drugs are more potent to this end than opium and its derivatives, and in particular morphia and codeia. The hypodermic use of the morphia salts, judiciously resorted to, constitutes our most valuable therapeutic resource in fulfilling the threefold indication of relieving cough, alleviating both the head-pain and the pains in the extremities, and in procuring sleep. The old-time dread of opium in influenza was not well founded. The administration of this drug in moderate doses is attended with advantages that far outweigh any danger of increasing the tightness across the chest and retarding expectoration. It is necessary to observe the same caution in giving it to infants and aged persons in influenza that is necessary under other circumstances. The influence of carbolic acid in restraining cough makes it a useful addition to soothing draughts in this disease.

The substernal and other chest-pains may be combated with sinapisms, turpentine stupes, repeated inunctions of fatty substances containing extract of belladonna, and the like. Pleurodynic stitches call for similar measures; a long strip of machine-spread belladonna plaster, about five centimetres (two inches) in width, applied very firmly to the side of the chest from the spine in a direction downward and forward parallel with the ribs, and reaching to the median line in front, affords great relief to the lateral chest-pains.

The control of the debility must be regarded as the most important indication in old and feeble persons. Wine, spirits, milk-punch, ammonia, spirits of chloroform, are to be used, not in accordance with fixed rules, but as occasion may require. In many cases wine or whiskey will be indicated from the beginning, the quantity being determined rather by the effect upon the circulation and the general condition of the case than by rule. Women and others unaccustomed to the use of alcoholic drinks often take wine and brandy in considerable quantities, with striking benefit and without flushing or other evidences of its disagreeing.

Chloral is inadmissible as a hypnotic by reason of its depressing effect upon the heart. Paraldehyde may be used, or the bromides in connection with opium if the latter alone is not well borne.

Diarrhoea must be managed in accordance with general principles. If slight, it does not require special treatment. It is apt to occur at one period or another in the course of most cases, and not infrequently marks the beginning of convalescence. Colic may be treated with warm fomentations and carminatives; if it be due to constipation, mild laxatives are to be combined with them.

Severe cases of influenza demand the careful attention of the physician, who must be on the alert to detect the inflammatory lung complications which so often lead up to the fatal issue as early as possible. Their treatment must be regulated by the circumstances of the case, the nature of the particular complication, the age of the patient, and so on, in accordance with general therapeutical indications.

Finally, all measures, of whatever kind, that tend to depress the general nervous system or the functional activity of the respiration, and especially the heart-power, are to be sedulously avoided in the management of influenza. During the convalescence unfavorable influences of the weather are to be guarded against. It is important to warn the patient that a severe attack of influenza renders him liable for some time afterward to pulmonary disorders. The sequels, and in particular those implicating the respiratory tract, are to be appropriately treated. After severe cases a course of tonics is commonly of advantage, and a change of climate often necessary to re-establish the health.

As bearing on what is stated in the foregoing pages on the causation of influenza, reference may be made to the investigations of Seifert,²⁴ who claims to have found in the mucus expectorated by patients with influenza numbers of a peculiar micrococcus. It is evident, however, that no conclusions can be based upon these observations until the results have been subjected to careful examination in other epidemics.

²⁴ Volkmann's klinische Vorträge, No. 240, June 20, 1884.

DENGUE.

BY H. D. SCHMIDT, M.D.

SYNONYMS.—Break-bone fever, Dandy fever.

HISTORY.—The history of this disease dates only from the second half of the last century, though it appears very probable that previous to this time dengue existed in the tropical regions of Africa and Asia, whence it was carried to Europe and America.

In Spain the disease has been known since 1764, when, up to 1768, it prevailed in Cadiz and Seville under the name of la piadosa or la pantomina.¹ In 1780 it appeared in the form of an epidemic in Philadelphia, where it was first noticed and described by Rush under the name of bilious remitting fever, commonly called break-bone fever on account of the violent pains attending it. Next it prevailed in Calcutta in 1824, and two years afterward it made its first appearance on the southern coast of the United States, in Charleston and Savannah, where it prevailed to 1827. Toward the close of 1827 another dengue epidemic broke out in the West Indies, whence the disease proceeded to the American continent, reaching New Orleans in the spring, and visiting Charleston and Savannah in the summer and autumn of 1828.² In 1844 it showed itself in Mobile, and in 1848 in Natchez, whilst in 1850 it reappeared along the Southern seacoast, particularly in Charleston, from which it proceeded even to inland towns, such as Augusta, Ga.³ In 1865 dengue appeared in Teneriffe and other Canary Islands, whilst at the same time and through the years 1866 and 1867 it prevailed in Andalusia and in some other Spanish provinces.⁴

¹ R. H. Poggio, La calentura roja observada in sus apariciones epidemicas de los anos 1865 y 1867, Madrid (reported in Virchow und Hirsch's Jahresbericht für das Jahr 1871, vol. ii. p. 200).

² G. B. Wood, Practice of Medicine, 4th ed., vol. i. p. 444.

³ S. H. Dickson, Elements of Medicine, 2d. ed., p. 747.

⁴ R. H. Poggio, Virchow und Hirsch's Jahresbericht für das Jahr 1871, vol. ii. p. 200.

One of the most extensive epidemics of dengue prevailed from July, 1870, to January, 1871, in Zanzibar,⁵ on the East Coast of Africa, whence it extended to Aden in Arabia and Port Said in Egypt. In December, 1871, the disease appeared simultaneously at Bombay and Calcutta,⁶ to which place it had been carried by transport-ships from Aden. Proceeding from Bombay in a northern direction along the railroad, it spread over the central regions of the North-western Provinces, the Rajputana states, Cashmir, and the Punjaub. From Calcutta it passed over Assam and Bhotan to Thibet, and thence downward into Burmah and to all the large cities along the coast; while it also extended along the coast of Malabar over Visigapatam to Madras and Pondichery, finally arriving at Mysore. Thus the disease had actually spread over the whole Peninsula from Cape Tutikorin to the foot of the Himalayas, attacking equally all races or nationalities without regard to age, occupation, or position. Forty years previously, however, an epidemic of dengue had prevailed in Burmah. In 1873 it appeared on the island of Mauritius, to which it had been carried from India by an emigrant ship. In the same year a considerable number of cases of dengue were observed in New Orleans. In 1877 it appeared again in Egypt, where it prevailed in Ismailia.

⁵ J. Christie, "Remarks on Kidniga Pepo, a peculiar form of exanthematous disease epidemic in Zanzibar, East Coast of Africa, from July, 1870, to January, 1871," Brit. Med. Journal, July 1, 1872, p. 577 (reported in Virchow und Hirsch's Jahresbericht für das Jahr 1872, vol. ii. p. 203).

⁶ Virchow und Hirsch's Jahresbericht für das Jahr 1873, vol. ii. p. 208.

Finally, in 1880, dengue, in the form of a very extensive epidemic, prevailed once more along the Southern coast, visiting equally Charleston, Savannah, and New Orleans. A number of valuable observations concerning the nature and symptoms of the disease were made during this epidemic by Drs. D. C. Holliday of New Orleans, J. G. Thomas of Savannah, and F. T. Porcher and J. Forrest of Charleston.⁷ At the same time it prevailed at Alexandria⁸ (Egypt) to such an extent as to affect nearly the whole population.

⁷ The papers of Drs. Holliday, Thomas, and Porcher were read before the American Public Health Association at its annual meeting, December, 1880, and published in the Proceedings of the Association. Dr. Forrest's paper was published in the American Journal of Med. Science, April, 1881.

⁸ A. Vernoni, "Le Dengue à Alexandrie d'Égypte en 1880," Gaz. hebd. de méd. et de chir., 41, 42 (reported in Virchow und Hirsch's Jahresbericht für das Jahr 1880, vol. ii. p. 5).

Dengue has been known under various popular names which it received from the people of the particular localities where it appeared in epidemic form. Even the designation, dengue, itself, by which the disease is at present generally known to the medical profession of the leading civilized nations, is of popular origin,⁹ for it is supposed to be a Spanish corruption of the word dandy, the name of dandy-fever having been jocosely conferred on the disease by the negroes of St. Thomas from the stiff carriage of those affected with it. At Zanzibar it received the popular name of kidniga pepo, signifying spasmodic pains.

⁹ G. B. Wood, Practice of Medicine, 4th edit., vol. i. p. 444.

DEFINITION.—Dengue is a peculiar febrile disease, generally appearing epidemically in tropical or semi-tropical regions, and characterized by a single paroxysm with or without remissions, severe pains, and stiffness in the joints and muscles, a peculiar exanthematous eruption, and almost never terminating fatally.

SYMPTOMS, COURSE, AND DURATION.¹⁰—Dengue never commences with a decided chill, though in many cases the attack of the disease is preceded by a feeling of general uneasiness and depression, vertigo, and headache, or even by a slight chilliness—a condition which may last from a few to twelve or even eighteen hours. In the majority of cases, however, the disease appears suddenly, very frequently at night, and announces itself at once by pains and a feeling of stiffness in the muscles, joints, back, and loins; in severe cases the pain may even extend to the bones.¹¹ The larger and smaller joints are equally affected, either simultaneously or successively, and frequently swollen, those of the hands and feet generally before the others. The pain in the joints is increased by motion, and is therefore justly regarded by most authors as rheumatic in nature. The same may be said of the muscles. Sheriff even observed redness of the skin covering the joints. According to the degree of severity of the case these pains may be more or less intense. In some cases hyperæsthesia of the skin of the palms of the hands and of the soles of the feet has been observed.

¹⁰ Judging from the various accounts rendered by a considerable number of observers, it appears that the clinical symptoms of dengue had been the same in all the different localities on the globe where it has hitherto prevailed epidemically.

¹¹ M. Sheriff, "History of the Epidemic of Dengue in Madras in 1872," Med. Times and Gazette, Nov. 15, p. 543 (reported in Virchow und Hirsch's Jahresbericht für das Jahr 1873).

Simultaneously with the affection of the joints and muscles the fever commences; its duration is from four to five days on the average, with one or, in exceptional cases, even more remissions. The temperature of the body during the first and second days of the fever rises to 102, 103, or even to 105° F; it then declines, to return to the normal standard on the fifth day. According to the measurements made by the late Dr. D'Aquin¹² of New Orleans, the temperature curves of dengue showed a continuous and steady rise until the highest point was reached on the first, second, or third day of the attack; then comes a short stadium of a few hours, and then a remission, soon to be followed by another rise of temperature, which, however, never reaches the maximum point of the first. The pulse rises with the temperature of the body, generally to from 80 to 120 beats a minute, and subsequently declines with the temperature. Delirium is very rarely observed in adults, but frequently in children, though without aggravation of the other symptoms. The face is generally flushed, the eyelids swollen, and the eyes injected and watery. The tongue in the beginning of the disease is covered with a white fur; its edges are red and its body swollen. As the disease advances the coating increases in thickness and assumes a dirty yellow color. The appetite is lost, without excessive thirst. In many cases there is slight irritability of the stomach, accompanied sometimes with nausea, though vomiting rarely takes place. The condition of the bowels is variable. The urine is small in quantity, and highly colored in some cases, whilst in others it has been reported to be pale and copious, and rich in phosphates in the beginning of the disease; it seldom shows any sediments and very rarely contains albumen. The disease generally reaches its acme on the third or fourth day, when the fever commences to subside, and an amelioration of the other symptoms takes place, so that the patient feels greatly relieved. This, however, is only of short duration, for not many hours afterward the fever rises again, while the other symptoms also increase in severity. At this time an exanthematous eruption appears upon the upper part of the body, the face, neck, breast, and shoulders, which in the course of two days extends over the whole body. Simultaneously with the appearance of the eruption the lymphatic glands of the back of the head and those of the neck, axillæ, and groins commence to swell; in severe cases the mucous membranes of the nose, mouth, and pharynx also become congested. The eruption, which is attended with much heat, itching, or even pain, is not uniform in character; for while in some cases it may represent a simple rash or erythema, it resembles in others the eruptions of scarlatina, rubeola, lichen, or urticaria. Frequently it is very light and evanescent, showing itself only for a few hours, and perhaps in the majority of cases it does not appear at all. In the severer cases it generally remains two days, when it commences to fade and disappear with desquamation, while at the same time the fever subsides and disappears entirely, though the stiffness and soreness in the joints and muscles, together with the inflammatory condition of the superficial lymphatic glands, may persist for many weeks. In exceptional cases the eruption, after an intermission of a few days, reappears, generally with greater intensity and with an aggravation of the other symptoms. In others, again, it has been observed to remain a whole week.

¹² D. C. Holliday, "Dengue or Dandy Fever," read before the Amer. Publ. Health Assoc. at New Orleans, December, 1880.

Hemorrhages from the nose and gums are also occasionally observed. Holliday even observed the occurrence of black vomit in the cases of two female children, aged respectively six and twelve, in the same family, who had suffered from yellow fever in 1878; they both recovered from the attack of dengue, though they were extremely ill and much prostrated. In female patients an attack of dengue not unfrequently causes the reappearance of the menstrual flow, while the pains attending the disease equally predispose to premature labor in pregnant women.

In severe cases of dengue the prostration following upon the subsidence of the fever is very great, for the patient is affected with a general weakness both of body and mind, indicating a great loss of nervous energy. In some cases observed by Slaughter the memory for names and words, as well as the ability for correctly writing even short sentences, was lost for one or two weeks after the commencement of convalescence. In children also cases are reported in which the mind remained affected for a short time after the attack. The convalescence in dengue, therefore, is comparatively slow, particularly as the pains in the muscles and joints, as already mentioned, pass away only gradually.

The duration of the disease, including the stage of convalescence, of course depends upon the degree of intensity of the attack, and accordingly varies in different cases. In a great number of cases dengue manifests itself only in its milder form. The average duration of the disease is from three to six days.

PATHOLOGY.—The pathological changes taking place in the different organs during the course of dengue are unknown, on account of the almost constantly favorable termination of the disease. From the peculiar features of some of the clinical symptoms accompanying the disease, however, we may speculate to a certain extent upon the nature of the pathological processes to which they are due. The sudden appearance of the characteristic pains in the muscles and joints, but particularly those in the head, neck, and loins, accompanied by a comparatively high fever, evidently point to the presence of an infectious poison in the system, though the question whether the noxious influence of this poison primarily affects the blood or the nervous system will be difficult to answer. But, judging from the early appearance of the pains, as well as from the physical and mental depression of the patient, we may presume that the nervous system is involved from the very beginning of the disease, and that the pains depend upon a hyperæmic condition of the affected parts, probably caused by a vaso-motor paralysis. The great resemblance of the painful affection of the muscles and joints in dengue to that of acute articular rheumatism leads to the supposition that the pathological condition in these joints is the same in both diseases; this view appears to be held by the majority of medical observers. In dengue, as in rheumatism, the pain due to the pressure of the hyperæmic and swollen tissues upon the irritated sensory nervous filaments is increased by motion—a phenomenon generally absent in neuralgia. The persistent headache, restlessness, and want of sleep, as well as the delirium and loss of memory observed in the severer cases, furthermore indicate a hyperæmic condition not only of the pia mater, but even of the brain-substance.

It is to be regretted that the literature of dengue within our reach shows no record of a quantitative analysis of the urine, from which we might have learned the quantity of urea secreted during the different stages of the disease, and which might have enabled us to form some idea of the extent of the destruction of the albuminous substances during the febrile stage, though, judging from the high grade of fever observed in the severer cases, we may well presume that the interchanges of matter are considerably augmented during this stage; while, on the other hand, the great nervous prostration of the patient directly after the subsidence of the fever, as well as the tardy convalescence, sufficiently shows that a large part of this waste is derived from the nervous tissues. The exanthematous eruption, representing a hyperæmia, or even an inflammation, of the skin, furthermore contributes to depress the nervous system by the pain and itching which it causes. This eruption, together with the inflammation and swelling of the superficial lymphatic glands, we are inclined to associate with the final elimination of the infectious poison from the organism.

Very little also is definitely known about the condition of the remaining organs, such as the kidneys, liver, and alimentary canal. The examinations of the urine in dengue recorded in literature are very few in number, and appear too unreliable for drawing any definite conclusions from them with regard to the condition of the kidneys. As albuminuria is met with in other infectious diseases, it is not impossible that it has also occurred in severe cases of dengue; though from the favorable termination of the disease it appears quite improbable that organic changes take place in these organs. In the same way may the liver be functionally deranged, or, judging from the destruction of matter during the febrile stage, a slight fatty infiltration of the organ may even occur—conditions which are apt to pass away with the exciting cause. The gastric irritability, whenever present, may be of nervous origin, though the vomiting, and particularly that of black hemorrhagic matters, observed in exceptional cases, evidently depends upon a hyperæmia of the stomach.

ETIOLOGY.—There is nothing positively known of the origin of dengue, but in perusing the accounts given by a number of medical observers from the different localities of the globe where it prevailed, we may presume that it existed in some parts of Asia and Africa long before it appeared in Europe and America. Perhaps the earliest record of dengue is the one dating from Cadiz and Seville, and concerning the epidemics prevailing in the cities in 1764 and 1768, when it was believed by the people that the disease had been imported from Africa. In Zanzibar (Christie), during the epidemic of 1870, the older native inhabitants remembered that fifty years before the disease had prevailed in this place. The Arabians living at this island also had known the disease in their own country, while the inhabitants hailing from the East Indies had never seen it. From the accounts of other writers we may presume that dengue has been known in Arabia for many generations. But, leaving aside its origin, it is authentically known that wherever dengue has appeared it has almost always been in the form of an epidemic, spreading from place to place and from family to family, without respect to race or nationality, to age, occupation or position, until every one susceptible to the disease was affected. Slaughter reports from India that even domestic animals, especially dogs and cats, were not exempt, as they appeared to suffer from rheumatoid affections of the joints.

Although toward the end of the last century dengue once prevailed epidemically in the temperate zone, at Philadelphia, it must nevertheless be considered as a disease especially at home in the tropical and semi-tropical regions, where it prefers to haunt low lands, particularly along the sea-coast, leaving almost untouched more elevated places. Though nothing definite is known about its special cause, its history and symptoms evidently show that it is not only infectious, but also highly contagious, in its nature, and in consequence must be caused by the entrance of a specific poison into the system. This view is held by the great majority of physicians residing in the various localities of the globe where the disease has prevailed. But, contagious as it may be, it greatly distinguishes itself from other contagious diseases by almost never proving fatal. As dengue generally prevails in the summer season and disappears with the approach of cold and rainy weather, its cause is apparently subject to the influence of certain meteorological conditions.

DIAGNOSIS.—When dengue appears epidemically, it is distinguished from other diseases without difficulty. The only disease with which it might be confounded when appearing in a sporadic form is acute articular rheumatism. But even from this affection it may be distinguished in its earlier stage by the pains not being limited to the joints, as is generally the case in articular rheumatism, but being also present in the head, back, and loins. Dengue is, moreover, characterized by a general physical and mental nervous depression, while in rheumatism the mind almost always remains clear. In the latter stage the peculiar eruption and painful swelling of the superficial lymphatic glands in dengue decides the question.

It has frequently been stated that dengue resembles yellow fever, and some physicians have even regarded it as a mild form of this disease. In examining attentively, however, the temperature of the patient during the febrile stage, it will be found that while it steadily rises in yellow fever, it is remittent in dengue. There is, furthermore, a difference observed in the state of the pulse, which in yellow fever generally falls on the third day, while the temperature continues to rise; in dengue, on the contrary, the pulse rises with the temperature. In the condition of the stomach also dengue considerably differs from yellow fever, for while in the latter disease this organ is almost always irritable, and vomiting is very frequently present, it is but rarely affected in dengue. The urine in yellow fever very frequently contains albumen as soon as the third day; in dengue, almost never, so far as the analyses recorded enable us to judge. Finally, the absence of jaundice and the appearance of the eruption on the fourth or fifth day remove all doubt about the nature of the disease. There are a number of other points by which dengue may be distinguished from yellow fever, which we, however, forbear to enumerate, for the reason that those already mentioned will suffice for a correct differential diagnosis.

PROGNOSIS.—Dengue, as has been stated before, scarcely ever terminates fatally unless it is complicated by some intercurrent disease. The prognosis, therefore, is highly favorable.

TREATMENT.—Nearly all authors recommend a symptomatic treatment in dengue, beginning with a mild cathartic, mercurial or not, and followed by a mild diaphoretic. To relieve pain and procure sleep opium—either uncombined or in the form of Dover's powder—belladonna, camphor, assafoetida, valerian, etc. have been recommended by different physicians; liniments containing camphor or chloroform have also been used with advantage for the same purpose. Foot-baths have been recommended to relieve the headache. To relieve the stiffness of the muscles and the articular pains after the subsidence of the fever iodide of potassium appears to be a favorite remedy in the East. Colchicum combined with aconite is also recommended for this purpose, as well as artificial sulphur baths and massage. The nervous depression during convalescence is to be combated with tonics and with regulation of the diet. Quinia appears to be generally discarded as a remedy in dengue.

RABIES AND HYDROPHOBIA.

BY JAMES LAW, F.R.C.V.S.

SYNONYMS.—Canine Madness, Rabidus Canis, Canis Rabiosa. Greek, Lyssa, Lytta, Lyssa Canina, Cynolyssa, Hydrophobia, Pantephobia, Ærophobia, Phobodipsia, Erethismus Hydrophobia, Clonos Hydrophobia, Dyscataposis. French, Tetanus Rabien, La Rage, Toxicose Rabique. German, Wuth, Hundswuth, Tollwuth, Wuthkrankheit, Hundtollheit. Italian, Rabbia, Arabiata. Spanish, Rabia, Rabiosa. Swedish, Hundsjuka. Roumanian, Turbarea.

DEFINITION.—Canine madness is an acute infectious disease, supposed to arise spontaneously in the genus Canis (dog, wolf, fox, etc.) and Felis (cat, etc.), but transmissible by inoculation to the other Mammalia and to birds. It is characterized by a long period of incubation, by exaggerated reflex excitability, by disorder of the intellectual, emotional, and other nervous functions, by change of habits, by extreme irritability of temper, by optical and other delusions, by spasms of the muscles of the eyeballs and throat, by paralysis, and by more or less fever. The disease runs a short and almost without exception fatal course.

HISTORY.—Plutarch claims that hydrophobia was first recognized by the Asclepiadæ, and Homer's allusions to the malign dog-star and to Hector's acting like a raging dog have been quoted as implying a knowledge of rabies. We find no certain reference to the affection, however, until we come to Democritus and Aristotle, in the fourth century B.C. The latter clearly describes the disease and uses the name lytta, but, singularly enough, claims for man an exemption from the general susceptibility to the infection by inoculation.¹ From that date to this the successive outbreaks, sufficiently noteworthy to secure a place in history, are so numerous and widespread as to show a continuous prevalence of the malady in the Old World, and, since the early part of the eighteenth century, in the New.

¹ Historia Animalium, lib. viii. cap. 22.

GEOGRAPHICAL DISTRIBUTION.—Rabies is more prevalent in temperate regions than in the tropics and Arctic Circle, but this is common to all animal plagues propagated solely or mainly by contagion, and is manifestly due chiefly to the density of population, the activity of commerce, and the free movement of men and animals in the temperate zone. That a hot or cold climate is incompatible with rabies is disproved by its prevalence under the tropics in Southern China, India, Abyssinia, the West Indies, Peru, Chili, and Brazil, and in the Arctic Circle in Northern Greenland, Lapland, Siberia, and Kamtchatka. On the other hand, many islands and secluded regions in the temperate zones maintain a continued immunity or have been invaded only recently by the introduction of infected dogs. We may instance the Hebrides, Australia, Tasmania, New Zealand, South Africa, West Africa, the Azores, St. Helena, and, until the last half century, La Plata, Malta, and Hong-Kong. The disease is well known throughout North Africa, Arabia, Syria, Turkey, and Asia generally, in Ceylon and other of the East Indian islands. It is also notorious that even when unusually prevalent its progress is often abruptly arrested by a considerable river, and Schrader and Virchow both notice that though it ravaged both banks of a river, yet the islands in the river escaped, as was notorious of the islands in the Elbe during the great Hamburg epizoötic in 1852-53. While, therefore, rabies prevails most extensively in the more civilized countries and in large cities, yet we can point to no geographical area in which the contagion has failed to spread among those bitten by rabid animals, nor to any locality in which the disease has been shown to arise spontaneously from unwholesome conditions of climate, soil, or general environment.

ETIOLOGY.—We know of but one efficient cause of rabies—namely, infection. Yet as many conditions are believed to favor its extension, or even to determine its spontaneous eruption, it is necessary to speak of them shortly.

As shown above, climate cannot be charged with the generation nor diffusion of rabies. Many countries formerly thought exempt are now known to suffer. The following may be named: The East and West Indies, Syria, Egypt, Cyprus, Siberia, the lands north of the Baltic, and South America. Others manifestly maintain their exemption only because the morbid germ has not yet been introduced.

Certain seasons undeniably show a far wider extension of the disease than others, but such epizoötics are not limited to a particular season or year, and, unless cut short by human intervention, cover a succession of years of the most varied climatic character, spare inaccessible or secluded islands in the very centre of the outbreak, and the cycles of prevalence will succeed each other, in place of occurring simultaneously, in closely adjacent countries subject to the same climatic vicissitudes, but separated by narrow seas. Even a broad river destitute of bridges usually abruptly arrests an epizoötic, and protects the land beyond lying under precisely the same general influences. In this connection may be quoted the recent great epizoötic of 1856-72 in England, which succeeded, but did not accompany, that of 1851-56 in Germany. Prof. Röll reports the extraordinary prevalence of rabies at Vienna in 1814, 1815, 1830, 1838, 1842, and 1862—years remarkable for diversity rather than uniformity of climatic characters.

Popular opinion refers rabies to the extreme heats of summer, and each year dogs are muzzled or otherwise confined by order of municipal authorities during the dog days, though left at liberty throughout the rest of the year. In 1780, Andry observed that the coldest and hottest months furnished the least number of cases, and later Hurtrel D'Arboval claimed that in France dogs suffered most in May and September, and wolves in March and April. Bouley claims that the majority of dogs suffer in March, April, and May. The following statistics are interesting in this connection:

Cases of Rabies in

WINTER. SPRING. SUMMER. AUTUMN.

Dec., Jan., Feb. March, April, May. June, July, Aug. Sept., Oct., Nov.

Dogs 755 857 788 696 (Bouley).

Men 17 25 42 13 (Boudin).

The increase of cases of rabies canina in the spring and summer months, as shown by the above statistics (7-15 per cent.), cannot reasonably be attributed to the influence of the weather, since even the strongest advocates for spontaneity would at once decline to claim any such ratio of spontaneous developments. The increase must therefore be mainly, if not altogether, due to the increased number of inoculations; and these latter are provided for in the jealousies and quarrels in the troops of males that follow each rutting bitch in spring, the principal period of oestrum in the canine female. The infection spread in this way in early spring tends to remain more prevalent throughout the hot summer months.

With regard to the greatly enhanced mortality in man during the summer months, as shown in Boudin's statistics for France, in the absence of any genuine hydrophobia in man apart from inoculation from a rabid animal, it may be attributed to three principal causes: 1st. The bites sustained from rabid dogs in spring and early summer, when the disease is most widely spread among these animals, will give rise to hydrophobia weeks or months later. 2d. In the warm season the body is more thinly clad and the hands and other portions are more frequently left bare, so that the teeth are less likely to be cleansed of the virulent saliva by passing through the clothes before entering the skin. 3d. The languor, fever, and nervousness attendant on extreme heat tend not only to hasten the activity of any disease-germs actually present in the system, but also strongly favor the increase of that nervous fear which so often generates a fatal pseudo-hydrophobia (lyssophobia) in persons that have been bitten by dogs.

Hunger, thirst, and spoiled food are invoked as causes of rabies, yet in the East, where the dogs are the scavengers of the cities and often suffer severely from hunger and thirst, eat the most offensive carrion, and drink the foulest water, the disease has a very restricted prevalence, while in South Africa and Australia the outcast and sheep-dogs, often the victims of starvation and thirst, entirely escape. Bourgelat, Dupuytren, Majendie, Breschet, and others have cruelly destroyed dogs by privation of food and water and by exposure under a broiling sun, but no rabies, nor anything resembling it, was produced. Dogs perspire little and suffer severely from heat, but there is no evidence that this can develop canine madness. It is claimed that Rossi of Turin developed rabies in cats by withholding food and drink, but, as he furnishes no inoculation-tests confirmatory of its virulence, the claim cannot be endorsed. Experiments with an exclusive diet of salt meat, putrid meat, and water only have failed to produce rabies.

The large preponderance of male dogs attacked with rabies has been constantly remarked by writers. Of 1990 rabid dogs reported by different authors, 1746 were males and 244 females—a ratio of more than 7 to 1. This excess of males attacked is much higher than the ratio of males in the dogs of the districts drawn upon. Thus, Bourrel found a ratio of 6 rabid males to 1 rabid female, while in his patients generally the proportion was 4 to 1. Leblanc found that 14 per cent. of the male dogs went mad, while but 1 per cent. of the females suffered. That sex is no protection against inoculated virus is shown by the frequent inoculation of castrated dogs of both sexes. The excess of male subjects may be attributed mainly to the frequency with which these bite each other when following a female in heat, and the respect of all alike for the latter sex. Even in the rabid dog the sexual instinct rises above the propensity to bite in the early stages of the malady.

Toffoli claims that he has caused spontaneous rabies by shutting up several dogs in a loose box with a bitch in heat and allowing them to fight for the prize. Weber and Leblanc have noticed similar occurrences. But Greve and Menecier have repeated the experiments with a contrary result; so that it remains probable that when successful the victims had already been inoculated before they were shut up. Moreover, the seclusion of male canine animals for a lifetime in menagerie cages, often adjoining those of their corresponding females, has never been known to induce rabies.

The bite of the violently enraged dog, and the bites mutually given when following a rutting bitch, are popularly supposed to cause rabies; but if this were the case, the disease must have been universally prevalent. The idea that the bite of a dog will cause hydrophobia should that dog at any subsequent period go mad is a similar delusion. Men doubtless occasionally develop lyssophobia under such an influence, but animals do not contract genuine rabies.

Dogs are alleged to have gone mad from violent suffering after an operation, and cats from being scalded or robbed of their kittens, but all such causes are continually operating without such effect, and when in a solitary case rabies develops, it can only be looked on as a coincidence.

Much popular prejudice exists against certain breeds, and the Pomeranian has been virtually ostracised on account of its supposed liability to rabies; but statistics show that the liability to contract the affection bears a relation to the exposure rather than the special breed. Eckel, Pillwax, and Hertwig found that dogs kept as house- or watch-dogs, and most pampered and confined, are the most liable, while St. Cyr and Peuch found the greatest number of cases among those running at large and allowed the freest exercise.

There is a popular belief that the bite of the skunk (Mephitis mephitica) is always rabific. Rev. H. C. Hovey describes a number of cases of infection from this animal,² and John G. Janeway has reported other instances.³ Both claim that the disease is spontaneous in the skunk, and Mr. Hovey holds, on very insufficient grounds, that the affection is a distinct variety of rabies (rabies mephitica). The facts seem to warrant only the conclusion that skunks in certain districts of Michigan and Kansas have had rabies communicated to them, and follow the rabid impulse to bite other animals and men. The Mephitinæ abound in the Eastern States, but we never hear of them stealing up and biting men or dogs, nor of the latter contracting rabies from skunk-bite. Eastern dogs frequently kill skunks and sustain bites, but do not thereby contract rabies. Even in Kansas this evil influence of the skunk-bite was unknown until 1870, showing that it is not inherent in the climate nor soil, but has been presumably imported. The spontaneity of the affection is assumed, not proved.

² Amer. Jour. of Science and Art, May, 1874.

³ New York Medical Record, March 13, 1875.

In the above epitome of alleged causes we find nothing proving the spontaneous evolution of rabies. The prevalence of the affection in wolves, foxes, jackals, cats, skunks, etc. proves nothing for spontaneity, more than its existence in the dog. In all these species of animals the malady develops the dread propensity to bite, and thus in all alike provision is made for the perpetuation and propagation of the malady. Unless a previous attack by a rabid animal has been observed, owners usually insist that their dogs have contracted the malady spontaneously, yet a rigid scrutiny will almost always reveal a strong probability, at least, of inoculation. The rabid dog wanders far from home, and sometimes accomplishes wonderful feats of leaping to reach his victim, so that his presence in a district is not even suspected, and animals thought to be safely secluded inside high walls suffer from his fangs. He is more inclined to bite and rush on than to stay and devour, and thus small animals, like the skunk, when bitten may survive to propagate the disease in places to which a dog could not possibly find access. Much circumstantial evidence makes strongly against the theory of spontaneity. Thus, the immunity of the islands of the Elbe in the very midst of a severe and protracted epizoötic, the continued immunity of the Hebrides and of Malta, each famed for its indigenous race of dogs, for long centuries, during which the malady prevailed at frequent intervals on the adjacent mainlands, and the continued exemption of South Africa and of the Australasian and other islands, in the face of the counter-fact that the affection persisted after importation in the West Indies and South America, speak strongly for the doctrine that the introduction of a pre-existing germ is an essential condition of the evolution of the disease. The following statistics of cases which entered the Berlin Veterinary College furnish further corroborative evidence. There entered the college,

In 9 years, 1845-53, inclusive, 278 rabid dogs.

In 1854, 4 rabid dogs.

In 1855, 1 rabid dog.

In 1856, 1 rabid dog.

In 5 years, 1857-61, inclusive, 0 rabid dog.

The average for each of the first nine years was a fraction less than 31. In the two last of the nine the cases rose to 68 and 82, and this led early in 1854 to an order for the muzzling of all dogs, which was rigidly enforced by the police. The disease was promptly suppressed, the two cases in the two succeeding years being probably due to infected kennels or to importation from without. The results in Eldena (Fuertenberg) and Holland (Van Capelle) are equally conclusive. The inefficiency of some orders for the muzzling of dogs makes nothing against these facts. A law on the statute-book is not always a law in force, as I saw in Alfort and Lyons in 1863; the dogs wore their muzzles only in honor of the periodic visits of the commissionnaire of police, and rabies prevailed.

The great majority of competent observers of to-day deny, or at least strongly doubt, the occurrence of the disease apart from inoculation. Without assuming to decide the question for all times and places, it may be safely asserted that there is no sufficient proof of such an occurrence in any recent time.⁴

⁴ Mr. Sâzé, a former student, informed me that boys in Japan produce what is believed to be canine rabies by administering to dogs a fungus (bukeryo) found growing on a coniferous tree. The dogs do not all seem to die, but are usually killed by way of precaution. The symptoms are those of delirium, with a propensity to bite, and the disease is assumed to be communicable, though no facts are given to show that it is so. This popular fancy has all the air of a popular fallacy, but as the counterfeit attests the genuine, it shows the familiarity of the Japanese with true rabies.

The contagion of rabies is usually resident in the saliva, but is by no means confined to that product. Paul Bert found the bronchial mucus virulent in dogs in which the saliva was non-virulent. The flesh has conveyed the disease when eaten, though probably only because of sores or abrasions on the alimentary tract. Smith records the death of negroes in Peru from eating rabid cows;⁵ Schenkius, that of persons who ate of a rabid pig; and Gohier and Lafosse have infected dogs by feeding the flesh of rabid dogs and ruminants; Rossi and Hertwig have separately induced rabies by inoculating sound animals with portions of nerves from rabid ones. No absolute proof can be adduced that the disease has been conveyed through consumption of the milk. Cases quoted to show its virulence are open to the objection that the dam probably licked the offspring. A similar uncertainty attaches to the spermatic fluid. Women are alleged to have acquired hydrophobia by coitus, but no such case can be adduced among animals, though rabid males have often had connection with healthy females. The alleged cases in women were therefore probably the result of an excited imagination or caused by virus introduced through some other channel. The breath and perspiration seem incapable of becoming media for the transmission of the disease. The blood was supposed to be non-virulent by Breschet, Majendie, Dupuytren, Blaine, Youatt, etc., but has been shown by Eckel and Lafosse to be rabific. Eckel successfully inoculated the blood of a rabid he-goat on a sheep and that of a rabid man on a dog. Lafosse accomplished the same in one of three attempts by inoculation from dog to dog. The blood is probably only virulent in the advanced stages of the disease, and its virulence implies the virulence of all vascular tissues.

⁵ Peru as it Is.

The saliva of rabid Herbivora and Omnivora, long held to be harmless, is now known to be virulent. Berndt has successfully inoculated it from an ox to four sheep; Eckel from a goat to a sheep; Rey from sheep to sheep; Lessona from an ox to two horses and a sheep; Tombaro from a heifer to a sheep, a horse, and two dogs; Youatt from horse and ox respectively to dogs; Ashburner from an ox to fowls; King from a cow to fowls; and Majendie, Breschet, Eckel, Hertwig, and Renault from man to dog; and Earle from man to rabbits. Besides these are a series of accidental cases, as from horse to man (Youatt), from a sheep to its shepherd (Tardieu), and from man to man (Aurelianus, Enaux, Chaussier).

Experiments by Hertwig and Eckel seem to show that saliva loses its virulence on the supervention of cadaveric rigidity or putrefaction in the dead body. Haubner even believed dried saliva to be innocuous. Yet Count Salm successfully inoculated the dried saliva of a rabid dog, and Schenkius reports a case of hydrophobia produced by a scratch of a hunting-knife that had been used to kill a mad dog some years before. A veterinary student at Copenhagen cut his finger while dissecting the body of a rabid dog twelve hours after death, and died of hydrophobia six weeks later. These cases in man may, it is true, have resulted from fear, but the same cannot be said of the infection of hound after hound placed in empty infected kennels, as recorded by Blaine, Youatt, and others. In the face of this it would require very strong negative testimony, indeed, to prove that the virus of rabies is devitalized in drying—a process which prolongs the vitality of other virulent matters.

Up to the present time the germ of rabies has not been demonstrated. That it is a particulate living organism may be reasonably deduced from its power of indefinite increase—a quality possessed by no mere chemical nor mechanical agent, also from the saliva proving non-virulent after filtration through plaster, while the solid residue left on the filter was virulent (Bert). But, although bacteria have been found in the saliva, those demonstrated up to the present are manifestly ordinary aërial bacteria, such as in Pasteur's experiments produced septicæmia rather than rabies. It still remains, therefore, for some future observer to discover that germ of which we cannot doubt the existence.

The point of election of this germ appears to be mainly the nervous tissue. Pasteur found the brain-matter of rabid animals invariably infectious, and has preserved the moist brain in an infecting condition for three weeks at a temperature of 12° C. He found that by direct inoculation in the brain-substance the period of incubation was abridged, rabies often showing itself in six, eight, or ten days. In the face of Rossi's successful inoculation of nerves and Pasteur's results with brain-matter it is difficult to account for the unsuccessful inoculation of nerve-tissue in six successive experiments by Hertwig. It seems to show that though the virus is concentrated in the brain, and especially in the medulla and pons, yet it does not equally permeate the entire nervous system. This election of the poison for the nervous tissue led Dr. Douboue in 1851 to advance the theory that it is propagated from the seat of inoculation to the brain through the medium of the nerves—a position now assumed by Pasteur. This, we fear, is not well founded. The poison, advancing for a month or more along the lines of the nerves, would probably derange and abolish their functions, as it does so speedily and effectually that of the nerve-centres after it has gained a seat in them, whereas, in reality, the local paralysis only appears in the last stages and after the symptoms of cerebral disorder are well established. Furthermore, a common premonitory symptom of rabies is congestion, swelling, and irritation of the inoculation wound, showing a sudden extraordinary activity at that point as a herald, if not a condition, of the general infection, whereas under a slow propagation along the nerves from the first this irritation would probably have been greatest in the wound at the outset, and would have thereafter kept pace with the progress of the virus along the nerves. Again, the blood is not always infecting. Blaine, Youatt, and others of the older observers had no fear of the blood. Hertwig obtained rabies in two cases only out of eleven inoculations with the blood of rabid subjects. The blood in this, as in some other diseases (variola equina, v. ovina, lung plague of cattle), proves to a certain extent inimical and destructive to the poison. Galtier inoculated nine sheep and one goat by intravenous injection of the saliva of mad dogs, in no case with fatal results nor indeed with any manifestation of rabies, but with the effect of fortifying the system so, that subsequent inoculation into the tissues of the saliva of rabid animals was harmless. Test inoculations made in the tissues of other animals with the same virus used in his intravenous injections, and his subsequent inoculations of the animals so treated, invariably determined rabies. Pasteur repeated these intravenous injections in dogs with the result of rapidly inducing rabies in a fair proportion of cases. One of his cases produced in this way recovered, and thenceforward resisted all further inoculation with the virus. Others that did not perish from intravenous injection afterward died of rabies after inoculation in the brain. Unfortunately, neither Galtier nor Pasteur have reported how much virulent saliva was injected in any one case, so that we have no data as to whether the difference was due to the varying quantity of the virus introduced in the various cases. Lussana, an Italian physician, had already in 1878 experimented on two dogs by injecting into their veins the blood of a physician who died of hydrophobia. The blood was drawn by leeches and cupping-glasses, and five grammes were injected into each dog. One died on the twenty-fourth day, presenting the symptoms and post-mortem appearances of rabies. The second at the end of one hundred and forty days developed symptoms of rabies which lasted a month, when the animal was sacrificed, and nothing special found at the autopsy. The data do not warrant a very positive conclusion, yet they seem to imply that the receptivity on the part of the dog is greater than that of the small ruminants. They suggest, further, a greater relative potency in the battle for life of the blood-globules of the small ruminants with this unknown rabific germ. This antagonism between the blood of the ruminant and the germ of rabies finds a parallel in the case of other disease-poisons in their relations to the nuclei of the tissues. Thus animals may prove refractory to a small dose of the poison of anthrax, yet Chauveau has shown that this virus will overcome all native or acquired insusceptibility when administered in excess. The same is true of the poison of chicken cholera, which Salmon dilutes until it is non-fatal, though still affecting the system and conferring an immunity from its attacks in the future. So with the lymph of variola ovina, which Peuch diluted to 1/50 and injected with the effect of producing slight fever and immunity without vesiculation.

This view would imply that in ordinary cases (inoculation with a moderate amount of the poison) the virus is for a time localized in the vicinity of the wound; and this is further supported by the fact that thorough excision and cauterization of the wound some time after it has been received is still often protective. It is weakened by the fact that bites of dogs in the stage of incubation sometimes produce rabies, but it must be borne in mind that there is still a period between the passage of the living germ to the salivary glands and brain and the growth of the germ in the nerve-centres, so as to produce pathognomonic symptoms, during which both blood and saliva must be virulent.

The ratio of successful inoculations to the bites is very varied. Thus, out of 555 dogs reported to have been bitten by rabid dogs, 188 contracted rabies; out of 183 experimentally exposed till bitten or inoculated, 91 became mad; out of 73 cattle bitten, 45 became rabid; out of 121 sheep bitten, 51 succumbed; and of 890 persons bitten, 428 took hydrophobia (48 per cent.). Of 440 bitten by rabid wolves, 291, or 66 per cent., took the disease. Such statistics are, however, far from satisfactory. Of dogs reported mad, some have only suffered from epilepsy, convulsions, or colic, while of those bitten by the really mad dog, some have sustained simple bruises without any real abrasion; in other cases the teeth have been wiped clean by passing through thick wool, hair, or clothing, or even the flesh of other animals just bitten; in other cases the bite has been inflicted at a time when the virulence of the saliva was at its minimum, or in a subject which was naturally insusceptible. The protective effect of clothing was well illustrated in a case which came under my notice in London. Six animals bitten by a rabid dog all contracted rabies, whilst a man bitten a few hours before through the coat-sleeve, and who did not have the wound cauterized for a full hour after the bite, escaped. Bouley found that in 32 persons bitten in the face, 29 died of rabies (90 per cent.); of 73 bitten on the hands, 46 died (63 per cent.); of 28 bitten on the arms, 8 died (28 per cent.); of 24 bitten on the lower limbs, 7 died (29 per cent.); of 19 bitten on the body (usually multiple wounds), 12 died (63 per cent.). The high mortality from the bites of rabid wolves and skunks is mainly due to this habit of attacking the face and hands. As illustrative of insusceptibility may be quoted the poodle of Hertwig, which was inoculated nine times with unquestionably rabic virus without effect; also the pointer of Rey, which was seventeen times bitten by rabid dogs without harm; also the acquired immunity of Galtier's sheep and rabbits, above referred to.

INCUBATION.—In the dog this varies from 6 days (Pasteur) to 240 days (Bollinger). In the majority of cases it ends in from 20 to 50 days. Pasteur, by inoculating into the brain substance direct, reduced the incubation from 20 days to 6 days. In the horse the limits of reported cases are from 15 days to 92 days. In the ox incubation varies from 20 to 30 days; in sheep, from 20 to 74 days; and in swine, from 20 to 49 days in recorded cases.

In man incubation is believed to be often much more prolonged. In 6 per cent. of all cases it is from 3 to 18 days; in 60 per cent., from 18 to 64 days; and in 34 per cent. it exceeds 64 days (Hamilton, Thamhayn). Quite frequently symptoms of hydrophobia appear from three to six months after the bite; in a few the period is prolonged to one or two years, and in rare instances to seven (Schule), and even twelve years (Chabert). But all such cases of prolonged incubation in man are at the least extremely doubtful. Man often contracts a pseudo-hydrophobia as the result of fear, and is curable by moral suasion alone; and as no such protracted incubations are noticed in the lower animals, and as no one of these abnormally deferred attacks in man has been verified by successful inoculation on animals, it is prudent to reserve a full assent until they are supported by better testimony. A specimen of such cases is that recorded by Chirac, in which a cadet bitten at Montpellier afterward spent ten years in Holland, and then, returning and hearing that his fellow-cadet bitten by the same dog had died of hydrophobia, he also manifested the disease and died. Another is the case of a man who, after having been bitten, spent two years in prison, and then developed hydrophobia and died. A mind naturally erratic and rendered weaker and more susceptible by prolonged confinement would prey upon itself and exaggerate the danger when the subject had been forcibly presented. In all such cases the attending physician should feel bound in the interests of humanity to inoculate a dog or other animal and ascertain whether or not the disease is virulent. The value of such results in dealing with future cases of the same kind cannot be overestimated.

The period of incubation appears to be relatively shorter in the young (average 45 days) than the old (average 70 days), and is believed to be shortened by constitutional excitement from violent passion, fever, the heat of the weather, or electrical disturbances.

During incubation no sign of the disease can be detected; it is even said that the wounds heal with unusual rapidity; but it is certain that toward the end of the latency the cicatrix, alike in man and animals, tends to become sensitive, itchy, congested, and even the seat of papular eruptions. The vesicles (lyssi) which, according to Xanthos, Marochetti, and Magistel, appear near the opening of the sublingual glands within a few days (6 to 20) after inoculation, have not been found by any recent observer.

SYMPTOMATOLOGY.—Three forms of rabies in the dog are recognized—the furious, the paralytic, and the lethargic. The prodromata are, however, the same in all, so that these may be conveniently considered before the different types are noticed.

The premonitory symptoms are by far the most important, as if these are recognized the dog may be safely secluded or destroyed before there is any disposition to bite. Any sudden change in a dog's habits or instincts is ground for suspicion. Bouley well says that a sick dog is always to be suspected. In some cases there is unusual dulness and apathy, in others great restlessness, watchfulness, and nervousness. A morbid appetite, in house-dogs a tendency to pick up and swallow straws, thread, paper, pins, and other objects, or to devour their own dung and urine, is highly characteristic. A desire to lick cold smooth objects, as a stone, a boot, a piece of metal, or the nose of another dog, is often seen. Smelling and licking the anus or generative organs of another dog and the exhibition of sexual desire are frequent manifestations. An increased fondness for the owner, shown by fawning and licking, is occasionally seen, though more commonly there is a change from a formerly amiable temper to a morose, sullen, retiring, and resentful disposition. If a naturally quiet dog flies into a violent passion at the sight of another dog or a cat, and attempts to bite it, he should be carefully watched. If a social dog seeks seclusion and darkness, or if while crouching and shrinking from a blow (hyperæsthesia) he yet bears it without howl or whine, he is to be strongly suspected. Barking without object, constant moving, searching, and scraping, a disposition to tear wood, clothing, etc. to pieces, and, above all, an absence from home for a day or two, should beget grave apprehensions. The rabid bark or howl which is often heard early in the disease is hoarse, low, and muffled, partaking of the nature of both bark and howl, the first running into the second, and consists of one loud howl followed by three or four others progressively diminished in force and uttered without closing the mouth. Some rub the chaps with the forepaws as if to dislodge an offending body from the mouth; others reject bloody matter by vomiting; and others turn the head and eyes as if following imaginary objects, and snap at them. Finally, a tendency to bite, rub, or gnaw the wound is significant, and usually draws attention to the fact that the wound, long healed, is still red, sensitive, and swollen, or even papular. The conjunctivæ are usually congested, there is an increased nasal defluxion, and the skin of the forehead and over the eyes is drawn into wrinkles. This stage lasts from a half to two or three days.

Following one or more of the above symptoms, paroxysms of wicked fury come on, alternating still with periods of quiet, in which prodromata only are observed. The red congested eyes assume a fixed stare, often squint or roll as if following an imaginary object, at which the dog presently snaps. A paroxysm is ushered in by increasing uneasiness, frequent change of position, and a desire to escape, shown in rushing at the door, tugging at the chain, or gnawing the post and walls of the kennel. The tendency to bite and gnaw is further shown by seizing the straw or tearing to pieces wooden and other articles within reach, or even by the victim lacerating its own body.

The rabid howl becomes more frequent, and the rage and disposition to bite strange animals and persons merge into a mischievous desire to worry all that come in the way, the respect for former companions and friends being steadily lost as the paroxysm increases in violence. Yet for a considerable time the voice of a loved master recalls the suffering animal to some degree of self-control. If free to escape during such paroxysms, the dog expends his excitement in wandering, making long journeys of five, ten, or twenty miles, and flying at every animal or man he meets, especially if they increase his excitement by any noise or outcry. If the victim escapes destruction during one of these wanderings, he returns during a lucid interval exceedingly dangerous, for, though he may recognize or even fawn upon his friends, yet the demon of mischief is even more potent within him, and may be roused to sudden violence by any noise or excitement. The intervals of quiet are attended by a prostration proportionate to the violence of the previous paroxysm, and the animal usually seeks seclusion and darkness, where he may lie dull and torpid, but he may be roused at any time to a renewed paroxysm by any noise, disturbance, the presentation of a stick, or, above all, by the approach of another animal. During the paroxysm the animal is manifestly the subject of acute delirium, has hallucinations, snatches and bites at unreal objects, turns on his best friends, even his master, seizes and holds on to a stick or iron bar until the teeth are detached and the gums lacerated, bites his own body, even amputating tail, testicles, or toes with his teeth; a bitch deserts her puppies or worries them, and all follow the unconquerable impulse to wander and to wound living beings. The victim will sometimes manifest incredible strength in breaking his chain and scaling high walls. Twitchings of the muscles of the face, and even general convulsions, are sometimes seen. Food is usually rejected, or if swallowed is soon vomited. In the course of two or three days the furious stage merges into the paralytic one, first shown by paresis of the hind extremities and a swaying motion in walking, then by paralysis of the lower jaw, which hangs pendent and allows the escape of a viscid saliva. The palsy gradually extends over the whole body—a sure precursor of approaching death, which is rarely delayed beyond eight days, and never more than ten, from the onset. In this last stage the animal has become extremely emaciated, with dry withered hair, hollow flanks, and small weak pulse; he may at first rise on his fore limbs when disturbed, and even attempt to snap, but there is now little danger of a bite. Convulsions may alternate with the paralysis. The result is invariably fatal.

The peculiarity of dumb or paralytic rabies in dogs is that the last or paralytic stage supervenes at once on the prodromata, without any intervening period of acute delirium and fury. The animal is throughout dull, quiet, and depressed, and shows little tendency to bite, to wander, or to restless movement. The excitement of the sexual passion is the same as in the furious forms, and the howl is still emitted, though much more rarely. Soon the lower jaw drops from paralysis, allowing the saliva to drivel from the mouth, and the animal can only succeed in closing it momentarily under the greatest provocation to bite. Paralysis of the hind limbs and of the whole body speedily follows, and death ensues in from two to three days. As soon as the jaw is paralyzed the subject is unable to drink, eat, bite, or bark, and emaciation advances with extraordinary rapidity.

The lethargic or tranquil form of rabies in dogs is manifested neither by furious madness nor by palsy of the jaws, but the nervous prostration is shown in a profound lethargy and apathy. The patient curls himself up, and will not be roused by his master's voice, by any noise, disturbance, or even punishment; he makes no response to the caresses of his friends, and pays no attention to the food or drink they bring him, but remains in his place, growing daily more emaciated and lethargic, until relieved by death toward the tenth or fifteenth day of the illness.

Besides the three typical forms there are intermediate varieties, which are classed with one or other according as the symptoms of that type seem to predominate. The same virus, inoculated, will produce different types in separate individuals, the result seeming to depend more on the susceptibility of the subject than any special quality in the poison. With many notable exceptions it may be stated that, on the whole, furious rabies predominates in hounds, bull-dogs, and other less domesticated or naturally vicious and courageous breeds, while the paralytic and tranquil types attack especially house and pet dogs.

POPULAR FALLACIES.—It is a dangerous delusion to suppose that mad dogs have a dread of water and polished surfaces, that they will not eat or drink, that they froth abundantly from the mouth, and that they run with the tail drooping between the hind limbs. There is no hydrophobia in the dog or other domestic animal. The rabid dog drinks freely in the early stages of the disease, lapping even his own urine; later, he still laps, and even plunges his nose in water, though often unable to swallow; and in his wanderings he swims rivers without the slightest reluctance. The appetite is not entirely lost, though greatly impaired and usually depraved, all sorts of unsuitable, noxious, and disgusting objects being picked up and swallowed with avidity. Frothing from the mouth is exceptional in rabies, and the flow of saliva is rarely seen unless when the jaw is paralyzed and pendent. Carrying the tail between the legs is a symptom of all diseases attended by abdominal pain, and is by no means constant in rabies. During the paroxysms the tail is usually carried erect.

Foxes, jackals, and badgers attacked by rabies lose their natural shyness, enter villages, follow and bite other animals and men, and, like rabid dogs, die in an unconscious and paralytic condition. Wolves are affected like foxes, but are more dangerous because of their power, the ferocity of their attack, and their habit of flying at the face and hands. Rabid cats are more retiring than dogs, and show less disposition to attack, but when they do, use both claws and teeth, and especially on bare portions of the body. The cry is hoarse like that emitted during the period of rut. They usually die about the third or fourth day.

The rabid horse is the subject of violent excitement, nervousness, and fear. There are trembling, loss of appetite, rubbing and eversion of the upper lip, neighing, sexual excitement, and inclination to bite and kick. Delirium may be suspected, but during the paroxysms the true nature of the disease is betrayed by the unconquerable desire to bite, kick, and otherwise injure those about him. He will even gnaw the manger and kick the stall to pieces, or lacerate his fore limbs and flanks with his teeth. In the early stages there is the same tendency to lick and rub the wound, which becomes red and irritable, the same red glaring or squinting eyes, and the same jerking of the muscles, as seen in the dog, and the affection winds up in the same way, in paralysis and death in four or five days.

Rabid cattle lose appetite, become very restless and excitable, grind the teeth, lick the cicatrix, evert the upper lip, and otherwise show sexual excitement, bellow often in a loud, terrified manner, as if still apprehensive of the attack of the dog, paw and scrape the ground with the fore feet, butt and kick viciously, have twitching of the muscles, and finally paralysis and death in from four to seven days. When paralysis is coming on the hind feet are often drawn forward as in inflammation of the feet. The pulse and breathing are accelerated during the paroxysms, but I have not found the temperature raised.

Rabid sheep and goats present the same general symptoms, bleat hoarsely, but viciously, have sexual excitement, nibble the cicatrix, have muscular weakness, emaciation, and paralysis, and die in from five to eight days.

Rabid swine show much fear, restlessness, and excitability, hide under the litter, start violently at noises, grunt hoarsely, champ the jaws, show a great disposition to bite and to gnaw and tear objects to pieces, have dark red, glaring eyes, gape and yawn, and become weak and paralytic. Breathing is often labored, and the mucosæ and white skin assume a dull red or leaden hue. Death ensues as early as the fourth or fifth day.

In Herbivora and Omnivora a paroxysm is usually induced by the sight of a dog—a fact of importance in diagnosis.

Rabid skunks have naturally received but little study. They tend, however, to steal up to men and animals and bite some exposed part of the body, like the finger, ear, or nose, and as stealthily retire. It is claimed that their odorous secretion is suppressed.

Symptoms of Hydrophobia in Man.

In some cases the prodromata are altogether omitted, the disease setting in suddenly with spasms of the pharynx and inability to swallow. More commonly, the premonitory symptoms last from one to three days. The first symptom is often an itching, prickling, or more or less violent aching in the seat of the bite, and even of an aura, a numbness, or shooting pain extending from that point toward the heart. In such cases the wound is red or bluish, and even swollen. In other cases there is chilliness, a general feeling of headache, malaise, and prostration, with lack of appetite or nausea, gloomy forebodings, taciturnity, nervous excitability, and restlessness. That restlessness which in patients cognizant of the consequence of the bite often induces insomnia during incubation, now often shows itself in an inability to keep quiet or to remain in one position or place—the exact counterpart of the initial restless stage shown in the canine patient. The sleep is now even more broken and unrefreshing and disturbed by fearful dreams. The restlessness soon merges into intense nervous irritability. Though devoured by thirst, the patient is afraid of water, and the attempt to drink will cause slight spasms with a sensation of filling of the throat and difficulty of deglutition. Even the air blowing upon his surface produces nervous irritation and apprehension, and a sudden glare of sunshine or other strong light is still more injurious. The pulse is increased in frequency, hard, and small; the breathing accelerated, oppressed, with at times yawning, sighing, or sobbing; there is some redness of the fauces, vascular injection of face and eyes, with, in some cases, dilated pupils; nausea or oppression at the epigastrium, sometimes vomiting; and usually constipation, which cannot, as in dogs, be referred to the earth, sand, and unsuitable materials swallowed. Intelligence is unimpaired.

With or without some or all of the premonitory symptoms above described the patient is sooner or later seized with constrictive spasms of the pharynx and respiratory muscles, the immediate occasion being an attempt to swallow liquid or some sudden fright or excitement. So great is the agony produced by this attack that, though consumed by thirst, the patient will rarely afterward attempt to drink, and the mere sight or offer of water, the noise of liquid flowing from one vessel to another, or even the sight of the vessel in which liquid was contained, suffices to bring on a violent paroxysm. This hydrophobia is peculiar to the human being suffering from this disease, being rarely seen in rabid animals; and it serves to enormously enhance the agony and horror of the affection. During a paroxysm the dyspnoea is usually extreme; there is a gasping or sighing respiration, and shrill, inarticulate sounds or screams are emitted which have been likened to the bark of a dog. These are manifestly due to the threatened suffocation rather than to an attempt to bark. The sensations have been described as a rising of the stomach into the throat, while others felt as if the throat had turned into bone and could not admit nor pass on the liquid. The abdominal contractions are often well marked, and retching and vomiting ensue. This reflex irritability of the nerves of deglutition and respiration is followed or attended by a condition of the most intense hyperæsthesia and a great exaltation of the special senses. A deaf and dumb child is said to have heard distinctly at this stage. There are, besides, during a paroxysm, general muscular trembling and clonic spasms of the muscles of the trunk and extremities. The facial muscles are contracted, the nostrils dilated, the face and eyes red and injected, and the pupils dilated, producing a spectacle of the most intense agony. Even in the intervals the hyperæsthesia is so extreme that the slightest touch of an attendant, a current of air, the approach of a candle, or even the ordinary tones of conversation, produce extreme agitation and may precipitate a violent convulsive paroxysm. The duration of the paroxysms and of the intervals varies much, but in general terms the former increase rapidly in number and severity, while the latter are correspondingly shortened. Restraint serves to aggravate the paroxysm, while, according to Hunter, the earlier and lighter ones may be relieved by running. The intense excitement sometimes becomes manifest in the persistent talking, and it is noticeable that the patient is free from mental delusions. As it is impossible to swallow, the patient spits out the now viscid saliva on all sides—a feature, like the fear of water, peculiar to man. As the disease advances the paroxysms are marked by the most perfect hallucinations and delirium, which impel the victim to acts of insane violence toward every one and every thing about him. In these fits he will use every available means of offence, even to the snapping of the jaws, though on the subsidence of the fit he will often express the greatest regret and warn his victims to be on their guard when he finds another paroxysm coming on. In some few instances the delusions continue even during the remissions, and the patient remains possessed of a sense of suspicion and horror of all about him, and yet the fear of being left alone is usually greater still. The convulsions may become tetanic (as opisthotonos). They are habitually more severe in men than in women and children. During a convulsion the victim will at times become black in the face, and may die from suffocation, apoplexy, or nervous exhaustion.

Should he survive this danger the final paralytic stage sets in. The spasms gradually become weaker, reflex irritability is lessened, and a period of quiet, and even comparative composure, may ensue, during which the former sights and sounds fail to produce a paroxysm, and some patients even recover the power of deglutition; but muscular weakness and prostration become more extreme, the lower jaw may even drop, and the viscid saliva drivel from the lips; finally, stupor supervenes, and the patient dies in a state of profound coma or complete exhaustion. This last stage lasts from one to eighteen hours.

Cases are met with in the human subject, as in the dog, in which the paroxysmal stage is omitted in greater part or entirely. The patient complains only of oppressed breathing, and sighs deeply when he attempts to swallow, and paroxysms, if they occur at all, are very mild. Decroix indeed claims that if a person suffering from hydrophobia is kept in a dark room and perfectly quiet, no paroxysms appear. The malady is, however, none the less fatal.

DIAGNOSIS.—The diagnosis of rabies and hydrophobia is not usually difficult if the disease has progressed to its paroxysmal stage. The most pathognomonic features are the fact of a bite by a rabid animal and the evidence of lesions and an extraordinary irritability of the medulla oblongata, inducing severe reflex spasms of the muscles of deglutition and respiration under the influence of any peripheral irritation. The clonic nature of the spasms and the entire absence of trismus serve to distinguish it from tetanus. From pharyngeal anthrax and diphtheria attended with spasm it is diagnosed by the extreme exaltation of the special senses and the absence of any marked febrile reaction; from acute mania by the difficulty of breathing and deglutition, the more rapid heart-beats during a paroxysm, and by the marked hyperæsthesia and exalted reflex susceptibility, as well as by the perfectly lucid intermissions; and from epilepsy, in that the latter is not associated with the same hyperæsthesia, that the paroxysm is not developed by noise, movement, attempts to swallow, sight of water, etc., that the spasms are more universal, and that they do not recur often, nor can they be roused by the causes immediately producing those of hydrophobia. Hysterical cases can usually be recognized by the imperfection of the symptoms; the subject, not knowing all the manifestations of hydrophobia, naturally fails to produce them.